It is already known from European patent application No. 0 141 976 to evaluate the string tension indirectly by finding the natural frequency of the strings. Due to the known basic correlation between the string tension and the corresponding frequency, the string tension can be calculated from the frequency.
To evaluate the frequency of the membrane which is formed by mounting the strings in a crosswise manner onto the racket frame, the conventional methods employ acoustical or mechanical devices to induce a forced oscillation. The amplitude value of the membrane oscillation is determined by a transmitter (transducer), such as a piezo crystal, for example, affixed to the membrane and the inducing frequency is then varied in order to find the point of resonance which is identical to the frequency of the membrane.
As conventional methods recommend the use of a variable frequency generator to induce an oscillation, these methods are complicated and expensive.
It is therefore an important object of this invention to provide an improved method and device for measuring the tension of racket strings which are simple to use, give reliable results and which can be employed with a reduced amount of equipment.